TWI625948B - Twdm passive network with extended reach and capacity - Google Patents

Abstract

A communication system (100) includes a first multiplexer (320a), the first multiplexer having a first optical line termination signal (S _D1 ) and a second plurality One of the second optical line termination signals (S _Dn ) of the work group is multiplexed into a first multiplexed signal (S _DM ). The communication system comprises a second multiplexer (320b), to the second multiplexer via a second multiplex signal (S _UM) demultiplexing to have one of the first group of the third optical multiplexing circuit a terminal signal (S _U1 ) and a fourth optical line termination signal (S _Un ) having one of the second multiplex groups. Additionally, the communication system includes a third multiplexer (310) optically coupled to the first multiplexer and the second multiplexer, the third multiplexer configured to optical signals in a feeder ( S _Ta ) performs multiplexing/demultiplexing with the first multiplexed signal and the second multiplexed signal. The first optical line termination signal and the second optical line termination signal comprise an old upstream free spectral range, and the third optical line termination signal and the fourth optical line termination signal comprise an old downstream free spectral range.

Description

Time-division split passive network with extended range and capacity

The present invention relates to a time wavelength division passive optical network (TWDM-PON) architecture having a range and capacity.

A basic communication system includes a transmitter that converts a message into an electrical form suitable for transmission over a communication channel. The communication channel transmits the message from the transmitter to the receiver. The receiver receives the message and converts the message back to its original form. Optical fiber communication is an emerging method of using optical fiber as a communication channel to transmit information from a source (transmitter) to a destination (receiver). An optical fiber is a flexible transparent medium made of thin glass dioxide or plastic that transmits light between the source and the destination throughout the length of the fiber. Fiber optic communications allow data to be transmitted over a longer distance than other known forms of communication and at a higher bandwidth than other known forms of communication. Fiber optics is an improved form of communication over one of the wires because the light traveling through the fiber experiences less loss and is immune to electromagnetic interference. The company uses fiber optics to transmit telephone signals, Internet communications, and cable TV signals. A fiber to the home (FTTH) network or fiber access network uses fiber optics as the last connection to the service provider to connect to the end user. Fiber optic communication provides a very low signal loss and very high frequency bandwidth. These two properties allow service providers to connect directly to their end users from their central office (CO) using a passive fiber optic device, which creates capital and operational cost savings. As the demand for bandwidth continues to increase in today's Internet, fiber-to-the-home (FTTH) networks have become a good-looking technology for operators to wire their customers and renew their lines.

In an access network, upgrading from one technology to another or improving the network architecture can be due to hardware at a central office (CO) and at an optical network unit (ONU) located at the customer premises. It is difficult to update. Each optical line terminal (OLT) in the CO is servoed to one of the ONUs in the WDM network and to the plurality of ONUs in the TDM network. Therefore, upgrading the access network can be challenging due to the timing of hardware upgrades at the ONU. The present invention provides a system and method for upgrading and extending an access network to an upgraded/expanded architecture that allows for efficient use of feeder fibers and thus cost savings. This new architecture allows the CO to be combined with other PON networks (eg, Super PON), reducing operational costs and network management efficiency. One aspect of the present invention provides a communication system including a first multiplexer, a second multiplexer, and a third multiplexer. The first multiplexer (eg, MUX) is configured to have a first optical line termination signal of one of a first multiplex group (eg, TDM) and one of a second multiplex group The optical line termination signal is multiplexed into a first multiplexed signal. The second multiplexer (eg, DEMUX) is configured to demultiplex a second multiplexed signal into a third optical line termination signal having the first multiplex group and having the second multiplex One of the fourth optical line termination signals of the group. The third multiplexer is optically coupled to the first multiplexer and the second multiplexer. The third multiplexer is configured to perform multiplexing/demultiplexing between a feeder optical signal and the first multiplexed signal and the second multiplexed signal. The first optical line termination signal and the second optical line termination signal each comprise one of wavelengths in the old downstream free spectral range. Additionally, the third optical line termination signal and the fourth optical line termination signal each comprise an upstream wavelength of one of the old upstream free spectral ranges. Embodiments of the invention may include one or more of the following optional features. In some embodiments, the system further includes at least one of a first amplifier or a second amplifier. The first amplifier is optically coupled to the first multiplexer (MUX) and the third multiplexer (BAND MUX) and is configured to optically amplify the first multiplexed signal. The second amplifier is optically coupled to the second multiplexer (DEMUX) and the third multiplexer (BAND MUX) and configured to optically amplify the second multiplexed signal. In some examples, the first multiplex group includes a time division multiplexed passive optical network (TDM-PON) protocol and the second multiplex group includes a wavelength division multiplexed passive optical network (WDM- PON) protocol, where each wavelength is a point-to-point link. The first optical line termination signal and the third optical line termination signal each may have a first agreement. Furthermore, the second optical line termination signal and the fourth optical line termination signal may each have a second agreement different from one of the first agreements. In some embodiments, the system further includes a first optical line termination and a second optical line termination. The first optical line termination has an optical output coupled to the first multiplexer and an optical connection to the second multiplexer. The first optical line terminal transmits the first optical line termination signal and receives the third optical line termination signal. The second optical line termination has an optical input to the first multiplexer and an optical input to the second multiplexer. The second optical line terminal transmits the second (point-to-point) optical line termination signal and receives the fourth (point-to-point) optical line termination signal. The first multiplexer is further configured to multiplex a fifth optical line termination signal with the first optical line termination signal and the second optical line termination signal into the first multiplexed signal. The first optical line termination signal can have a first agreement. The fifth optical line termination signal can have the first multi-work group (TDM-PON) and a second agreement different from the first agreement. The second multiplexer is further configured to demultiplex the second multiplexed signal into the second optical line termination signal, the fourth optical line termination signal (point to point), and a sixth optical line termination signal. The sixth optical line termination signal has the first multiplex group and the second protocol. The system further includes a third line terminal having an output in communication with the first multiplexer and one of the inputs to the second multiplexer. The third optical line terminal transmits the fifth optical line termination signal and receives the sixth optical line termination signal. In certain embodiments, the system further includes a feeder fiber and an array of waveguide gratings. The feeder fiber is optically coupled to the third multiplexer and configured to communicate the feeder optical signal. The arrayed waveguide grating is optically coupled to the feeder fiber and configured to perform multiplex/demultiplex between the feeder optical signal and the plurality of optical network unit signals. Each optical network unit signal includes one of an upstream wavelength in the old upstream free spectral range and one downstream wavelength in the old downstream free spectral range. The system can further include a fourth multiplexer and a fifth multiplexer. The fourth multiplexer is optically coupled to the third multiplexer and configured to have a fifth optical line termination signal of the first multiplex group and one of the second multiplex group The optical line termination signal (point-to-point) is multiplexed into a third multiplexed signal. The fifth multiplexer is optically coupled to the third multiplexer and configured to demultiplex a fourth multiplexed signal into a seventh optical line termination signal having the first multiplex group and having An eighth optical line termination signal (point-to-point) of the second multiplex group. The fifth optical line termination signal and the sixth (point-to-point) optical line termination signal each comprise one of downstream wavelengths in the upgraded downstream free spectral range, and the seventh (TDM PON) optical line termination signal and the eighth (point to point) The optical line termination signals each comprise one of the upstream free spectral ranges to upgrade the upstream wavelength. The system can further include a feeder fiber and an array of waveguide gratings. The feeder fiber is optically coupled to the third multiplexer and configured to communicate the feeder optical signal. The arrayed waveguide grating is optically coupled to the feeder fiber and configured to perform multiplex/demultiplex between the feeder optical signal and the plurality of optical network unit signals. Each optical network unit signal includes one of the old upstream spectral range of the old type, the old downstream wavelength of the old downstream free spectral range, and one of the upgraded upstream free spectral ranges. And upgrading the second downstream wavelength in one of upgrading the downstream free spectrum range. The system can further include at least one of a first amplifier or a second amplifier. The first amplifier is optically coupled to the fourth multiplexer and the third multiplexer and configured to optically amplify the third multiplexed signal. The second amplifier is optically coupled to the fifth multiplexer and the third multiplexer and configured to optically amplify the fourth multiplexed signal. In some examples, the system also includes a third optical line termination and a fourth optical line termination. The third optical line terminal has one of an output in communication with the fourth multiplexer and an input in communication with the fifth multiplexer. The third optical line terminal transmits the fifth optical line termination signal and receives the seventh TDM-PON optical line termination signal. The fourth optical line terminal has an output of one of communication with the fourth multiplexer and one of communications with the fifth multiplexer, the fourth optical line terminal transmitting the sixth (point-to-point) optical line termination signal and receiving The eighth (point-to-point) optical line termination signal. Another aspect of the present invention provides a method comprising receiving a signal at a first multiplexer (MUX) and performing multiplex/demultiplexing between: a first multiplexed signal And a first optical line termination signal having one of the first multiplex groups and a second optical line termination signal (point-to-point) having a second multiplex group. The method also includes receiving a signal at a second multiplexer and performing multiplexing/demultiplexing between the following signals: a second multiplexed signal; and having one of the first multiplexed groups a three optical line termination signal and a fourth optical line termination signal having one of the second multiplexed groups. The method also includes receiving a signal at a third multiplexer optically coupled to the first multiplexer and the second multiplexer, and multiplexing/demultiplexing between the following signals: a feeder An optical signal; and the first multiplexed signal and the second multiplexed signal. The first optical line termination signal and the second optical line termination signal each comprise a downstream wavelength of one of the old downstream free spectral ranges, and the third optical line termination signal and the fourth optical line termination signal each comprise One of the upstream upstream free spectral ranges. This aspect may include one or more of the following optional features. In some embodiments, the method further comprises amplifying the first multiplexed signal at a first amplifier optically coupled to the first multiplexer and the third multiplexer; or The second multiplexed signal is amplified by the second amplifier of one of the optical connections of the third multiplexer. In some examples, the first multiplex group includes a time division multiplexed passive optical network protocol and the second multiplex group includes a wavelength division multiplex (WDM) passive optical network protocol, each of which The wavelength is a point-to-point link. The first optical line termination signal and the third optical line termination signal each may have a first agreement, and the second optical line termination signal and the fourth optical line termination signal may each have one different from the first agreement Second agreement. In some embodiments, the method further comprises receiving the following signal at the first multiplexer (MUX) and performing multiplex/demultiplexing between: the first multiplexed signal; a fifth optical line termination signal, the first optical line termination signal, and the second optical line termination signal. The first optical line termination signal has a first agreement, and the fifth optical line termination signal (TDM-PON, λ ₂ ) has the first multiplex group and a second agreement different from the first agreement. The method also includes receiving, at the second multiplexer, a signal that is multiplexed/demultiplexed between: the second multiplexed signal; and the second optical line termination signal, the fourth An optical line termination signal and a sixth optical line termination signal (TDM-PON λ ₂ ). The sixth optical line termination signal has the first multiplex group and the second protocol. The method can also include transmitting the feeder optical signal by one of the feeder fibers optically coupled to the third multiplexer. The method also includes receiving the feeder optical signal and the plurality of optical network unit signals at an array of waveguide gratings optically coupled to the feeder fiber, and between the feeder optical signal and the plurality of optical network unit signals Work / solution multiplex. Each optical network unit signal includes one of an upstream wavelength in the old upstream free spectral range and one downstream wavelength in the old downstream free spectral range. In some embodiments, the method includes receiving the following signal at a fourth multiplexer optically coupled to the third multiplexer, and performing multiplex/demultiplexing between the following signals: a third a multiplex signal; and a fifth optical line termination signal having one of the first multiplex groups and a sixth optical line termination signal having one of the second multiplex groups. The method also includes receiving, at a fifth multiplexer optically coupled to the third multiplexer, the following signals, and performing multiplex/demultiplexing between the following signals: a fourth multiplexed signal; One of the first multiplexed group has a seventh optical line termination signal and one of the second multiplexed group eighth optical line termination signals (point-to-point). The fifth optical line termination signal and the sixth optical line termination signal are each included in one of the upgraded downstream free spectral ranges, and the seventh optical line termination signal and the eighth optical line termination signal are each included in the upgrade upstream One of the upstream wavelengths in the free spectrum range. The method can further include transmitting the feeder optical signal by one of the feeder fibers optically coupled to the third multiplexer. The method also includes receiving the feeder optical signal and the plurality of optical network unit signals at an array of waveguide gratings optically coupled to the feeder fiber, and between the feeder optical signal and the plurality of optical network unit signals Work / solution multiplex. Each optical network unit signal includes one of the old upstream spectral range of the old type, the old downstream wavelength of the old downstream free spectral range, and one of the upgraded upstream free spectral ranges. And upgrade downstream wavelengths in one of the upgraded downstream free spectrum ranges. The details of one or more embodiments of the invention are set forth in the drawings and the description below. Other aspects, features, and advantages will be apparent from the description and drawings.

Fiber to the Home (FTTH) delivers a communication signal from a central office (CO) or optical line termination (OLT) to a household or a store via a fiber optic. Referring to Figure 1, today's FTTH systems are primarily provided by a point-to-multipoint time division multiplexed (TDM) passive optical network (PON), which is present in a single point-to-multipoint time division multiplexed passive optical network. Using a passive optical power splitter at one of the remote nodes 70 (RN) to share one of the co-transceivers 50 (OLT) at the CO 40, or through a point-to-point (pt-2-pt) direct connection, where In contrast to the transceiver (TDM transceiver), a home-run fiber is extended back to the CO 40 and each client is terminated by a separate transceiver. The PON 10 provides optical signals from a CO 40 to a number of optical network units (ONUs) 60 that each include a bidirectional optical transceiver at a customer premises and includes an optical transmitter/receiver or transceiver 50. A TDM-PON provides beneficial savings in terms of the number of feeder fibers 20 (between a remote node 70 and the central office 40) and the number of optical transceivers 50 at the CO 40 as compared to a point-to-point home system. At the same time, save the space of the patch panel for terminating the fiber. However, TDM-PON does not scale well with bandwidth growth. The bandwidth of each household is typically oversubscribed as the bandwidth of the optical line termination transceivers at each central office 40 is shared among all ONUs 60 connected to an OLT 50. The point-to-point system provides high frequency bandwidth to the end user 30; however, a large number of backbone fibers 20 and optical transceivers 50 are used point-to-point. Therefore, the point-to-point system does not scale well with the OLT 50 at the CO 40 and the fiber count between the CO 40 and the RN 70, resulting in greater space requirements, higher power, and an increased cost. Fiber to the home (FTTH) is considered the termination state of the broadband access network when the fiber provides virtually unlimited bandwidth. FTTH replaces the copper infrastructure currently in use (eg, telephone lines, coaxial cables, etc.). Multiplex systems are used in optical networks to take advantage of the large bandwidth of optical fibers to achieve one of their full benefits. Multiplexing enables the formation of several virtual channels on a single fiber. Therefore, the multiplexing of several optical signals increases the utility of a network infrastructure. Time Division Multiplex (TDM) is a method used to multiplex several signals onto one high speed digital signal on a fiber link. TDM multiplexes several signals by using different time slots to create different virtual channels. Wavelength Division Multiplexing (WDM) multiplexes these signals by using different wavelengths for different channels; these channels are generated by separate lasers and their traffic typically does not interact. With continued reference to FIG. 1, the CO 40 receives information that can be transmitted to the end user 30, such as video media distribution 42, internet material 44, and voice material 46. The CO 40 includes an optical line termination (OLT) 50 that connects the optical access network to an IP, ATM or SONET backbone, for example. Thus, OLT 50 is the endpoint of PON 10 and translates the electrical signals used by the equipment of a service provider and the fiber optic signals used by PON 10. Additionally, the OLT 50 coordinates the multiplexing between the switching devices at the user end 30. The OLT 50 transmits a fiber optic signal through a feeder fiber 20, and the signal is received by a passive remote node 70 that distributes the signal to a plurality of users 30. In some examples, each CO 40 includes a plurality of OLTs 50, 50a through 50n. Each OLT 50 is configured to provide a signal to a group of users 30. Additionally, each OLT 50 can be configured to provide signals or services in different transport protocols, for example, one OLT provides services in a 1G-PON and another OLT provides services in a 10G-PON (as will be discussed later) ). A multiplexer (MUX) combines several input signals and outputs one of the individual signals to combine the signals. The multiplexed signal is transmitted through a physical conductor (e.g., a single optical fiber 20), which saves the cost of having multiple conductors for each signal. As shown in FIG. 1, the CO 40 multiplexes signals received from a number of sources, such as video media distribution 42, internet data 44, and voice material 46, and multiplexes the received signals into one The multiplex signal is then transmitted to the remote node 70 via the feeder fiber 20. In addition, the CO 40 multiplexes the signals of each OLT 50 and then transmits the multiplexed signals to the set of remote nodes via the feeder fibers 20. The CO 40 includes a carrier source (e.g., a laser diode or a light emitting diode) for generating an optical signal that is carried by the multiplex signal to the end user 30. At the receiver end (i.e., ONU 60 at the user end), an inverse procedure occurs using a demultiplexer. The demultiplexer receives the multiplexed signal and splits it into separate original signals that are initially combined. In some instances, a photodetector converts optical waves back to their electrical form and is located at a remote node or at an end user 30 (eg, data on a network, converted to current using a microphone, and used) The loudspeaker is converted back to its original physical form of sound waves, converted to electrical current using a video camera and converted back to its physical form using a television). In TDM PON, signal demultiplexing occurs after the photodiode in the domain. One of the transceivers or ONUs 60 on the user side includes a carrier source (eg, a laser diode or a light emitting diode) for generating an optical signal to be sent from an end user 30. The information is carried to the CO 40. A laser is a high frequency generator or oscillator that requires one of the tuning, feedback, and decision frequency tuning mechanisms. The laser emits light in a homogenous manner such that the laser output is a narrow beam of light. In some embodiments, a laser includes a plurality of mirrors that provide a medium of amplification and frequency and provide feedback. Photons bounce off the mirror through the medium and return to another mirror to bounce for further magnification. One and sometimes two mirrors may partially transmit light to allow for a fraction of the light produced. A laser diode system has one of the active dielectrics of a pn junction electrically excited semiconductor laser. The pn junction is formed by doping (i.e., introducing impurities into a pure semiconductor to change its electrical properties). As shown, a feed fiber 20 is employed from CO 40 to a remote node 70, wherein the signals are separated and spread, for example, to optical network units 60a through 60n. Referring to FIG. 2A, the most commonly deployed TDM-PON system is a GPON system standardized by the ITU (International Telecommunication Union) and an EPON system standardized by the IEEE (Institute of Electrical and Electronics Engineers). A GPON system provides a 2.5 Gb/s downstream bandwidth and a 1.25 Gb/s upstream bandwidth shared among the subscribers 30 on the feeder fiber 20 and is coupled to the same OLT transceiver 50. GPON systems are mature and very cost effective. The difficulty of scaling the bandwidth of the TDM PON is due to the fact that the optical transceivers of both the OLT 50 and the ONU 60 need to operate with the aggregate bandwidth of all ONUs 60 sharing the same OLT 50. A TDM-PON can typically have a power separation ratio of 1:16 to 1:64. The average bandwidth per user and PON range is inversely scaled relative to the separation ratio. The TDM-PON architecture includes two wavelengths for separating the upstream transmission from the downstream transmission. In both G-PON and E-PON, the 1310-nm wavelength is used for upstream transmission from the ONU 60 at the customer premises to the OLT 50 at the CO 40 and the 1490-nm wavelength is used for the OLT 50 from the CO 40 The transmission of the ONU 60 at the location of the user 30. The upstream and downstream wavelengths are multiplexed on a single fiber 20, 22 by an optical wavelength duplexer 52 in front of a laser diode (LD) transmitter 54 and a photodetector (PD) receiver 56. . The optical signals from OLT 50 are separated in the field by a 1:N power splitter 72 to broadcast signals to a plurality of ONUs 60 that are servoed to different users 30. The distance between the OLT 50 and the ONU 60 is limited by the OLT/ONU transmitter power and receiver sensitivity as well as the separation loss. The OLT transceiver 50 is shared among the users 30 on the same power splitter 72 using a TDM protocol, thereby simplifying the cost of fiber termination at the CO 40 and spreading the transceiver 50 across multiple ONUs 60. Typical GPON and EPON designs use a separation ratio of 1:16, 1:32 or 1:64 and a transmission distance of up to 20km. An alternative FTTH architecture is the WDM-PON architecture shown in Figure 2B. A wavelength division multiplex (WDM) PON gives each user 30 a dedicated wavelength along each direction of transmission. In a WDM-PON network, a different wavelength λ is assigned to each user 30 for upstream transmission of data to the CO 40. Thus, each ONU 60 uses a wavelength specific transmitter 62 (such as a tunable wavelength laser) to transmit data to the CO 40 at different wavelengths λ. The tunable wavelength laser can be tuned for deployment for each particular path 22 (corresponding to a user 30), which allows one type of transceiver 60 to be used by all users 30. The WDM-PON system provides a larger overall system capacity FTTH network by multiplying the total capacity channel capacity by the number of wavelengths used. In this architecture, each customer ONU 60 has one of the OLT 50 transmitters at the CO 40. Thus, for 32 customers with 32 ONUs 60, the CO 40 has 32 OLTs 50 each transmitting a signal to an ONU 60. Signals from a CO 40 to an individual ONU 60 are carried using different wavelengths, and a wavelength multiplexer 200, 200a (typically an array of waveguide grating routers (AWG)) is used in the field in the fiber optic equipment 20, 22 work. Another wavelength multiplexer/demultiplexer 200, 200b inside the CO 40 separates the optical wavelengths in the feeder fiber 20 and connects the optical wavelengths to individual "color" OLT transceivers 50, 50a through 50n. Field AWG 200 typically has one of a plurality of free spectral ranges (FSR) cycling devices and the upstream and downstream wavelengths are separated by FSR, as shown in Figures 3A-3C. In Figure 2B, the two wavelength multiplexers 200 in the field and in the CO cycle the AWG. The TDM architecture and the WDM architecture can be combined into a time wavelength division multiplexing PON (TWDM-PON). In an example of a TWDM-PON architecture (as proposed in Figure 2C and proposed in the NG-PON2 effort (Next Generation PON2) proposed by ITU-T SG-15), one option of NG-PON2 is used. A four-wavelength integrated OLT 50. In NG-PON2, the OLT 50 uses four downstream transmitter lasers (LD-1, LD-2, LD-3, LD-4) and four upstream receivers combined with the duplexer 52 inside the OLT 50. (PD-1, PD-2, PD-3, PD-4). The NG-PON 2 employs one of the fiber optic devices 20 that is compatible with conventional TDM-PON, so all four transmission wavelengths in the OLT 50 are broadcast to each ONU 60 having only one receiver 66. Therefore, the ONU 60 needs to use a tunable receiver 66 to select individual downstream wavelengths. At the same time, the ONU 60 is also equipped with a tunable transmitter 65 to tune to one of the four possible receive wavelengths from an NG-PON2 OLT 50. The NG-PON2 ONU 60 needs to have a tunable transmitter 65 laser compared to the WDM-PON in Figure 2B where only the ONU transmitter 65 laser needs to be tunable (for inventory and easy operation). Both receivers 66 can be tuned to transform into more expensive hardware. In addition, NG-PON2 must also overcome the additional losses of power splitter 72 (the AWG 200 inherently has less than the power splitter loss for large turns compared to the AWG 200 used in WDM-PON) and ONU 60 Tunable filter loss. The goal of NG-PON2 is to increase system capacity by increasing the TDM rate (10 Gb/s per wavelength) and using multiple wavelengths to achieve more user 30 and/or higher frequency wide applications. However, this design faces power budget and cost challenges. Another challenge for NG-PON 2 is that both OLT 50 and ONU 60 need to manage both wavelength slots and time slots; and a new MAC layer protocol is required. One of the data link layers (layer 2) MAC layer data communication protocol reduction. The MAC software provides addressing and channel access control mechanisms to allow several terminals or network nodes to communicate with each other within multiple access networks. A media access control system implements the hardware of the MAC. The rapid increase in Internet applications is making the bandwidth available from current TDM-PON systems tense. Although the proposed WDM-PON and TWDM-PON solutions address access capacity issues to some extent, they are more expensive to deploy. In order to effectively overcome the long-term increase in bandwidth demand cost, one of the higher ONU counts per feeder fiber 20 shown in FIG. 3A is updated to accommodate the increase in bandwidth requirements and access ratios of the TWDM-PON architecture 100. The TWDM-PON architecture 100 (as shown and described with respect to Figures 3A-8, 9B, and 10) combines the cost advantages of supporting multiple users 30 (TDM-PON) on a single wavelength with the wavelength of WDM-PON Flexibility, this allows wavelengths to be specific to a particular user or application. The upgraded TWDM-PON architecture 100 uses one of the TDM and WDM technology\architectures set forth above (with respect to Figures 2A, 2B, and 2C) to enable the number of users 30 and the capacity that can be supported on a single PON. Multiply. The upgraded TWDM-PON 100 reduces the cost and construction time of the fiber infrastructure and shortens the network design cycle. In addition, the upgraded TWDM-PON 100 provides a thinner fiber bundle 20, 22 that will be used between the CO 40 and the RN 70 and between the RN 70 and the ONU 60, which results in a smaller pipe that is easier to deploy. In addition, the upgraded TWDM-PON 100 increases the coverage distance (ie, the length of the feeder fibers 20, 22) and achieves an excellent PON design, which allows the upgraded TWDM-PON 100 to be combined and reduces the number of COs 40 and reduces the network Long-term recurring costs in operation. In addition, the upgraded TWDM-PON 100 does not require a tunable receiver at the ONU 60, which significantly reduces the cost of the network 100. The upgraded TWDM-PON 100 can achieve a similar overall capacity (NG-PON2, 40 Gbps) of the feed fibers shown in Figure 2C with 16 wavelengths and current GPON speeds (2.5 Gbps downstream and 1.25 Gbps upstream). In addition, the upgraded TWDM-PON 100 is preferably scaled with the transmission distance on the feeder fibers 20, 22, and has a better power budget and dispersion tolerance (compared to NG-PON2). As previously explained, the TDM-PON uses one of the optical power splitters 72 at the RN 70 to connect multiple ONUs 60 to each OLT 50. When a large number of wavelengths are transmitted via an optical power splitter 72 in a TWDM-PON, each ONU 60 includes a blocking filter to block the band wavelength. In some examples, a tunable ONU 60 is used and includes a tunable narrowband filter. The use of a tunable ONU 60 increases the cost per ONU 60, which results in an increase in the cost of the network 100. In addition, the power splitter 72 at the RN 70 may not achieve a large separation ratio because the total power loss of a large splitter is difficult to overcome by the transmitters 54, 65 and receivers 56, 66 at the OLT 50 and ONU 60. of. Therefore, in the upgraded TWDM-PON architecture (Fig. 3A), it is desirable to use a wavelength selective (de)multiplexer such as a cyclic arrayed waveguide grating router (AWG) 200 to greatly increase the maximum separation ratio and remove the ONU The need for a narrowband filter at 60, thereby reducing cost (by not using a tunable receiver). In addition, the circulating AWG 200 decouples losses from several turns, thereby achieving a higher separation ratio with lower losses. The use of multiple TDM PONs of one AWG 200 (eg, 1G-PON and 10G-PON) can be considered a TWDM-PON due to the use of WDM to increase the overall capacity of the network. 3A-3E illustrate an exemplary arrayed waveguide grating 200 (AWG) for use in an upgraded TWDM-PON architecture 100. An AWG 200 can be used to demultiplex an optical signal in the upgraded TWDM-PON 100 (for example, at the RN 70 or at the OLT 50). The AWG 200 can multiplex a large number of wavelengths into one fiber, thus increasing the transmission capacity of the optical network 100. The AWG 200 can therefore multiplex channels of several wavelengths onto a single fiber at one of the transmission ends, and conversely, it can also demultiplex multiple wavelength channels at the receiving end of an optical communication network. . An AWG 200 system is commonly used in optical networks as one of a wavelength multiplexer and/or a demultiplexer passive planar lightwave circuit device. The N x N AWG 200 also has wavelength routing capabilities. If a system has N equidistant wavelengths λ _N An N x N AWG 200 can be designed with one of the matching wavelength spacings. The N x N AWG 200 routes the different wavelengths at an entrance port 210 to different exit ports 220 such that all N wavelengths are sequentially mapped to all N exit ports 220 _N . The routing of the same N wavelengths at the two consecutive inlet ports 210 shifts the wavelength map by one exit side. In addition, the wavelength channel on either inlet is repeated in FSR. In some embodiments, AWG 200 receives a first multiplexed optical signal via a first fiber at a first input 210a (eg, input 1). The AWG 200 demultiplexes the received signals and outputs a demultiplexed signal through its outputs 220, 220a through 220n (e.g., outputs 1 through 32). The AWG 200 is essentially cyclic. The wavelength multiplexing and demultiplexing properties of the AWG 200 are repeated over a wavelength period called the free spectral range (FSR). A plurality of wavelengths separated by a free spectral range (FSR) are transmitted along each turn 220. Thus, by utilizing multiple FSR cycles, different layer services can coexist on the same fiber optic device 20, 22. In certain embodiments, to construct a low loss cycle AWG 200, the star coupler and the waveguide grating should be carefully designed. Array waveguides in fiber gratings should be properly engineered. The phase difference between the waveguides in the grating determines one of the FSRs B1 to B4 of the AWG 200. The channel-by-channel loss-volume curve in an FSR B1 to B4 is related to the eigenmode of the output channel waveguide (the natural vibration of the AWG 200) and the overlap integral between the beamlets radiated from the waveguide arm in the grating. The end channels of any of the FSRs B1 through B4 typically have a large loss and tradeoff passband. Usually the best system design has about four or six more channels than the desired number of channels, so four or six bandwidth channels are wasted each cycle. The disadvantage of using a circular AWG 200 with one of the small FSRs is that the channel spacing can vary slightly between cycles. The wavelength spacing with respect to frequency can be relatively wide for shorter wavelengths. The waveguide arm phase difference, material dispersion (i.e., refractive index that varies with wavelength), and waveguide profile design all contribute to variations in channel spacing across the FSR. Channel spacing can be optimized by proper material selection and waveguide design, but it is very difficult to form a uniform frequency spacing across multiple FSRs. Thus, in some instances, a larger AWG 200 is used in combination with separator 72 (see, for example, Figure 4). AWG 200 can have multiple cycles of optical wavelength range with repetitive multiplex and demultiplexing properties. As shown in Figure 3C, each cycle B1 through B4 is commonly referred to as an FSR. A multi-cycle AWG 200 transmits multiple wavelengths λ separated by FSR along each of 220, 220a to 220d ₁ To λ ₁₆ . In most PON systems, different wavelengths are used upstream and downstream of the signal due to the near-far effect. The near-far effect is one in which a receiver picks up a strong signal and thereby makes it impossible for the receiver to detect a condition of a weaker signal. This allows the use of one of the wavelength selective devices, such as a thin film filter (TFF), to help achieve the required isolation between the uplink and the downlink to overcome the near-far effect. Therefore, it is assumed that a WDM-PON platform uses two FSR cycles of the cyclic AWG 200 for each layer of service (one cycle for downstream transmissions and another cycle for upstream transmissions). To add a second platform to a network 100, four available cycles will allow simultaneous use of both platforms. This system 100 will deliver signals from each of the two platforms to the user 30, and each AWG output 220 will output/receive signals from both platforms. Each AWG output 220 is optically coupled to at least one ONU 60, and then each ONU 60 will receive signals from both platforms. To further illustrate the use of the two platforms by using a recirculating AWG 200, FIG. 3C shows an AWG 200 having one input 210a and four outputs 220, 220a through 220b. The cyclic AWG 200 receives four FSRs (bands) B1 through B4, as shown in Figure 3D. FSR B1 and B2 are used upstream and FSR B3 and B4 are used downstream. FSR B1 contains wavelength λ ₁ To λ ₄ , FSR B2 contains wavelength λ ₅ To λ ₈ , FSR B3 contains wavelength λ ₉ To λ ₁₂ And FSR B4 contains wavelength λ ₁₃ To λ ₁₆ Where λ ₁ < λ ₂ < λ ₃ <....< λ ₁₅ < λ ₁₆ . When the circulating AWG 200 receives the wavelength λ at its input 210 ₁ To λ ₁₆ Time, each wavelength λ ₁ To λ ₁₆ Output from a different output 220 in a round-robin fashion. Therefore, the first wavelength λ of the first FSR B1 ₁ Output through the first output 220a of the circulating AWG 200, the second wavelength λ of the first FSR B1 ₂ Outputting through the second output 220b of the circulating AWG 200, the third wavelength λ of the first FSR B1 ₃ Output through the third output 220c of the circulating AWG 200, and the fourth wavelength λ of the first FSR B1 ₄ The first cycle is completed by outputting the fourth output 220d of the circulating AWG 200. When the first wavelength of the second FSR B2 is λ ₅ The second cycle begins when the first output 220a of the circulating AWG 200 is output, and the second wavelength of the second FSR B2 ₆ Output through the second output 220b of the circulating AWG 200, the third wavelength λ of the second FSR B2 ₇ Output through the third output 220c of the circulating AWG 200, and the fourth wavelength λ of the second FSR B2 ₈ The second cycle is completed by outputting the fourth output 220d of the circulating AWG 200. The third cycle is the first wavelength λ of the third FSR B3 ₉ The second wavelength λ of the third FSR B3 is started by the output of the first output 220a of the circulating AWG 200. ₁₀ Output through the second output 220b of the circulating AWG 200, the third wavelength λ of the third FSR B3 ₁₁ Output through the third output 220c of the circulating AWG 200, and the fourth wavelength λ of the third FSR B3 ₁₂ The third cycle is completed by outputting the fourth output 220d of the circulating AWG 200. The fourth cycle is the first wavelength λ of the fourth FSR B4 ₁₃ The second wavelength λ of the fourth FSR B4 is started by the output of the first output 220a of the circulating AWG 200. ₁₄ Output through the second output 220b of the circulating AWG 200, the third wavelength λ of the fourth FSR B4 ₁₅ Output through the third output 220c of the circulating AWG 200, and the fourth wavelength λ of the fourth FSR B4 ₁₆ The fourth cycle is completed by outputting the fourth output 220d of the circulating AWG 200. In this case, each FSR B1 to B4 contains four wavelengths λ ₁ To λ ₁₆ (FSR B1 contains wavelength λ ₁ To λ ₄ , FSR B2 contains wavelength λ ₅ To λ ₈ , FSR B3 contains wavelength λ ₉ To λ ₁₂ , FSR B4 contains wavelength λ ₁₃ To λ ₁₆ And the cyclic AWG 200 contains four outputs 220. Therefore, one wavelength from each of the FSRs B1 to B4 is outputted to each AWG output 220. In other words, each AWG output 220 outputs a wavelength from one of the FSRs B1 to B4. As illustrated, a first platform may use the first FSR B1 for upstream transmissions and a third FSR B3 for downstream, and the second platform may use the second FSR B2 for upstream transmissions and the fourth FSR B4 for downstream. Similarly, network 100 can support three platforms by using six FSR cycles, thereby providing three platforms to each user 30. The network can also provide four platforms by using eight FSR cycles, five platforms by using 10 FSR cycles, and so on. In a TWDM-PON architecture, each wavelength λ is responsible for multiple users 30, so network 100 can be configured to simultaneously operate PONs of different rates to supply different layer services (eg, 1G-PON and 10G-PON) ). For example, a service provider at the CO 40 may want to provide a business advancement service on a higher rate PON and a standard residential service on a lower rate PON. Referring to the example discussed with respect to FIG. 2C, the Business Advanced Edition service may use one of the first FSR B1 and the third FSR B3 or the second FSR B2 and the fourth FSR B4, and the low rate PON may use the first FSR B1 And the other of the third FSR B3 or the second FSR B2 and the fourth FSR B4. The services received by user 30 are determined by their respective ONUs 60, which are part of Customer Premises Equipment (CPE). The CPE can be configured to receive one or the other of a Business Advanced Edition service or a low rate service. In some instances, if user 30 wants to upgrade from a low rate service to a business upgrade service, user 30 must change/upgrade its CPE to be able to receive the upgraded/quality signal from the CO 40 transmission. Figure 3E shows that there are only four wavelengths each (λ ₁ To λ ₄ And λ ₅ To λ ₈ ) (of a total of eight wavelengths) of one of the two FSRs B1, B2. As shown, the same wavelength is used for the uplink and downlink. While this is atypical for most commercial PON systems today, there are many proposals for this technology, including their proposals to use reflective semiconductor optical amplifiers at the ONU 60. In addition, the signal at the entrance to the AWG 200 is for eight different TDM-PONs at eight different wavelengths (λ ₁ To λ ₄ And λ ₅ To λ ₈ ) Upload both the uplink signal and the downlink signal. The AWG 200 is cycled at the RN 70 using one of the FSRs having one of four wavelengths, thus transmitting two TDM-PON services along each of the exit ports 220a to 220d of the AWG. This system therefore works exactly the same as the system shown in Figure 3D, except that wavelength selective techniques such as TFF cannot be used as duplexers at the OLT 50 or ONU 60. Instead, an orientation device such as an optical circulator must provide all of the required optical isolation between the input and output. A wavelength selective component will still be used at both OLT 50 and ONU 60 to select the free spectral range. If this technology will become readily available in the future, after deploying a field AWG with the wavelength plan set forth in Figure 3D, it may be desirable to upgrade the service to use the same wavelength for upstream and downstream, thus implementing to each AWG exit埠Up to four different services. 4 shows a schematic diagram of one of the higher order architectures of the TWDM network 100 from the CO 40 to the ONU 60 associated with the end user 30. TDM-PON systems such as G-PON or E-PON are typically deployed commercial FTTH systems due to their cost and bandwidth efficiency. The system typically uses ratios such as 1:16, 1:32, and 1:64. In TDM-PON, increasing the separation ratio reduces the overall OLT cost and reduces the feeder fiber strands 20, 22, but also reduces the capacity and range to each user 30, since larger separators have a Great loss. For example, having a 1:32 separation ratio of one of 20,000 passes CO 40 means that a minimum of 625 fiber strands 20 must be used from CO 40 to RN 70. 3125 fibers 20 are required for a very large CO 20 of 100,000 channels. A larger service area means that the average distance between the user 30 and the CO is greater, thereby further increasing the amount of fiber required in the network. This large number of feeder fibers 20 makes the large CO 40 unattractive due to the high fiber cost and increased average time of recovery in the event of fiber cutting in one of the thick fiber optic cables 20. In addition, a larger sized pipe is used underground to accommodate the coarse fiber 20. For airborne fiber construction, thick fiber means heavy load on the pole. Thus, the upgraded TWDM-PON 100 reduces the number of feeder fibers 20, 22 from the CO 40 to serve the same number of users 30 by combining both TDM and WDM with a scalable TWDM architecture. As shown in FIG. 4, the upgraded TWDM-PON 100 includes a plurality of TDM-PONs stacked on a single feeder cable 20 using wavelength division multiplexing. Thus, if 10 pairs of wavelengths (covered by two FSRs of a ten-turn AWG) are used, then 10 TDM-PONs can be multiplexed onto a single feeder fiber 20, thereby enabling a feeder from a CO 40 The number of optical fibers 20 is reduced by a factor of ten. In some instances, an AWG 200 is used in the field to first separate the wavelength pairs. Each output 埠 220 of the AWG 200 is followed by a power splitter 72 to separate the TDM signals to the individual ONUs 60, as in a conventional TDM PON (Fig. 2A). The total number of users 30 or ONUs 60 per feeder fiber 20 is M × N ,among them M Is the number of outputs 埠 220 of the WDM separator (eg, AWG 200) and N The TDM power separation ratio of the power splitter 72. Therefore, the number of fibers, the size of the pipe, and the mean time to repair (MTTR) of a fiber cut are reduced. M One factor. FIG. 5A shows an upgraded TWDM architecture 100 representing a TDM-PON using a 1G-PON. However, the G-PON wavelength is shifted. "1G-PON λ1" at CO 40 means having one of the modified optical layers G-PON OLT 50, such that G-PON OLT 50 is transmitted on wavelength λ1 of FSR B1 upstream of cyclic AWG 200 and from corresponding downstream FSR B3 The pair is received at a wavelength λ9. In some examples, the 1G-PON OLT 50 transmits over the wavelength λ5 of the upstream FSR B2 of the circulating AWG 200 and is received from the pair of wavelengths λ13 in the corresponding upstream FSR B4. When the CO 40 includes more than one OLT 50, the signal of each OLT is signaled to other OLTs (e.g., the optical system 300 including the multiplexers 310, 320) prior to transmitting the signals of each OLT to the remote node 70. Do multiplex. In addition, FIG. 5A shows a discrete OLT transceiver 50 that allows a TWDM system to be piggybacked onto a commercial G-PON OLT chassis. Thus, to upgrade the network, an ISP switches the G-PON OLT transceiver to the transceiver 50 designed with custom wavelengths and plugs into the multiplexers 310, 320 and amplifier 330 (if needed). Discrete OLT transceiver 50 (as opposed to an integrated array OLT transceiver used in a WDM-PON) allows flexibility in using different protocols (eg, 1 G-PON and 10 G-PON), where each protocol is in one At different wavelengths (see Figure 5B). Referring to Figure 5B, in some examples, the wavelength λ1,1 of the cyclic AWG 200 is for the 1G-PON protocol (OLT 50aa), whereas the wavelength λ2,1 is for the 10G-PON protocol (OLT 50ab). Therefore, the ONUs 60 connected to the λ1,1 of the AWG output port 220 and suspended outside the power splitter 72 are all tunable 1G-PON-ONU 60 and connected to the λ2 of the AWG output port 220, and the ONUs 60 of all 1 are tunable. 10G-PON ONU. Referring back to Figures 5A and 5B, in some embodiments, an optical system 300 is included for separate transmission connections (downstream signal S _DM ) and receiving connection (upstream signal S) _UM A duplex fiber, which is different from a conventional G-PON OLT transceiver that includes a single fiber interface with one of the upstream and downstream signals separated by one of the upstream and downstream signals within the OLT 50. The optical system 300 includes a band multiplexer 310, a downstream multiplexer 320a for multiplexing signals from the OLT 50 (in the L red band), and a signal for receiving from the ONU 60 (in C red) In the frequency band, one of the demultiplexing solutions multiplexer 320b is performed. Band multiplexer 310 acts as a duplexer because it will upstream OLT signal S _DM (in the C red band) and the downstream OLT signal S _UM (in the L red band) multiplexed into a transmission signal S _T signal. The design of optical system 300 uses a downstream multiplexer 320a to pass downstream signals S from one or more OLTs 50. _D1 To S _Dn Multiple work into a downstream signal S _DM And using an upstream demultiplexer 320b to pass the multiplex upstream signal S _UM Solving multiplexes to one or more upstream signals S of each OLT 50 _U1 To S _Un . In one embodiment, optical system 300 can include a signal amplifier 330 and/or a signal preamplifier 340 in the downstream and upstream directions, respectively. Signal booster 330 and/or signal amplifier 340 can be an erbium doped fiber amplifier (EDFA). An EDFA is an optical repeater device used to increase the intensity of an optical signal carried through a feeder fiber. The EDFA signal amplifier 330 is optically coupled to the downstream multiplexer 320a and the band multiplexer 310 and enables the multiplexed downstream signal S by means of a higher power EDFA _DM Power increase, followed by multiplex downstream signal S _DM Entering the long fiber feeder 20 or one of the devices with large losses (eg, a power splitter), it reaches the ONU 60. The EDFA signal amplifier 340 is optically coupled to the upstream demultiplexer 320b and the band multiplexer 310 and causes the multiplexed upstream signal S _UM The increase in power. The EDFA signal amplifier 340 is positioned such that the multiplexed upstream signal S _UM Amplifying the multiplexed upstream signal S as a weak signal arrives at the optical system 300 _UM . Since the EDFA signal booster 330 includes signals S from multiple OLTs 50 _D1 To S _Dn Multi-process downstream signal S _DM Amplifying, and the EDFA signal amplifier 340 amplifies the signal S containing the plurality of OLTs 50 _U1 To S _Un Multi-process upstream signal S _UM Thus, the cost of each EDFA 330, 340 is then shared among all TWDM wavelengths λ, resulting in a cost effective upgraded TWDM-PON 100 architecture. In some examples, optical system 300 as illustrated uses a 1:32 way splitter 72 to extend the range of feeder fibers 20 from CO 40 to one of 50 kilometers. To achieve further scope, another set of EDFAs 330, 340 can be placed at the RN 70. However, placing the EDFAs 330, 340 at the RN 70 will change the RN 70 from a passive RN 70 to a powered RN 70. The use of EDFAs 330, 340 as part of optical system 300 is optional and depends on the scope and size of the upgraded TWDM-PON 100. In addition, the EDFA relaxes the requirements for the OLT 50 and ONU 60 transceivers, thereby reducing the required transmitter laser power and receiver sensitivity for both the ONU 60 and the OLT 50. With proper link design, EDFA's shared cost improves transceiver yield and reduces overall upgraded TWDM-PON 100 architecture costs. In some embodiments, the ONU 60 of the network 100 includes a tunable transmitter laser. Additionally, one or more of the output dies 220 of the AWG 200 can be optically coupled to a power splitter 72 for communicating an output signal from the AWG 200 to the plurality of ONUs 60. Connecting the power splitter 72 to the AWG 200 to achieve a separation over the overall loss of the power splitter provides the upgraded TWDM-PON 100 and thus increases the scalability of the upgraded TWDM-PON 100. As illustrated, the ONU 60 can include a tunable laser; however, a non-tunable laser can also be used. Since each ONU 60 receives/transmits a signal at a particular wavelength λ, a laser is used to transmit a signal at the correct wavelength. Thus, an ISP can use multiple ONUs each having a different laser to accommodate the different wavelengths received. In some embodiments, the edge outputs 埠 220a, 220b, 220m, 220n of the AWG 200 are connected to a point-to-point (point-to-point) WDM-PON transceiver at the ONU 60. Since the upgraded TWDM-PON 100 is configured to use discrete transceivers at the CO 40, the transceiver 50 can be point-to-point WDM or TDM due to the ease of mixing wavelength-specific TDM-PONs with point-to-point WDM-PONs on the same fiber optic device 20. transceiver. In some examples, the upgraded TWDM-PON 100 can include 20 wavelengths. The ISP can reserve 16 wavelengths for the TDM-PON and reserve four edge wavelength channels for the point-to-point pure WDM transmission (ie, edge outputs 埠 220a, 220b, 220m, 220n), and two edge wavelength channels at each end of the AWG. . The edge channels of an AWG 200 (i.e., edge outputs 埠 220a, 220b, 220m, 220n) typically suffer from higher losses. Thus, these channels (i.e., edge outputs 埠 220a, 220b, 220m, 220n) are used for point-to-point connections that do not pass through the lossy power splitter 72 (resulting in more power loss). Point-to-point WDM-PON channels can be used to carry premium services, such as 10Gbps enterprise network connections that require guaranteed bandwidth. As previously stated, to upgrade or add upgraded TWDM-PON 100 capacity, it is often desirable to have multiple services or platforms stacked on the same fiber 20. For example, in the TWDM-PON architecture 100, multiple services are stacked by using a different pair of wavelengths (one for the upstream and one for the downstream) for each platform that is stacked as illustrated with respect to Figure 3D. . As shown, the ISP updates or extends the upgraded TWDM-PON 100 with repeated FSRs B1 through B4 of the cyclic AWG 200. Referring back to FIG. 3D, four FSRs B1 through B4 are shown, and the upgraded TWDM-PON 100 can use the first FSR B1 (upstream FSR) and the third FSR B3 (downstream FSR) for existing services, and is used for upgraded or extended services. Second FSR B2 (upstream FSR) and fourth FSR B4 (downstream FSR). Or the upgraded TWDM-PON 100 can use the second FSR B2 (upstream FSR) and the fourth FSR B4 (downstream FSR) for existing services, and use the first FSR B1 (upstream FSR) and the third FSR for upgraded or extended services. B3 (downstream FSR). The FSRs B1 to B4 are staggered such that the upstream and downstream wavelengths are separated from each other, which makes the duplexer inside the ONU 60 easy to design. Each ONU receiver (of the transceiver) is equipped with a band filter to select the desired FSRs B1 through B4 for the particular service of interest. Therefore, a tunable receiver is not required at the ONU 60. Referring to FIGS. 5C and 5D, each ONU 60 includes a duplexer 62 that multiplexes the first 埠P1 and the second 埠P2 of the duplexer into a third 埠P3. The signals on the first 埠P1 and the second 埠P2 occupy the disjoint frequency band, that is, on different FSRs B1 to B4; therefore, the signals on the first 埠P1 and the second 埠P2 can coexist on the third 埠P3 . Therefore, two shorter wavelength bands, FSR B1 and FSR B2, are used for the uplink and two longer wavelength bands, FSR B3 and FSR B4, are used for the downlink. This relaxes the requirements for the color duplexer in the ONU 60. In addition, each ONU 60 includes a bandpass filter 64 in front of the duplexer 62 to remove unwanted downlink channels from the OLT 50 for other services. The fixed bandpass filter 64 passes frequencies and wavelengths λ within a particular range and rejects (i.e., attenuates) frequencies or wavelengths λ outside of the range. Thus, each bandpass filter 64 passes the desired wavelength λ associated with the desired service. In some embodiments, the duplexer 62 inside each ONU 60 also acts as a bandpass filter 64 in front of the receiver Rx to remove unwanted downstream links from the OLT 50 for other services. Channel. FIG. 5C shows an exemplary ONU 60 configured to receive/transmit one of the signals on the first FSR B1 and the third FSR B3. While FIG. 5D shows an exemplary ONU 60 configured to receive/transmit one of the signals on the second FSR B2 and the fourth FSR B4. Referring back to FIGS. 5A and 5B , system 100 can include one or more optical splitters 72 in communication with each output 220 of AWG 200 . Optical splitter 72 further expands network 100. Each optical splitter 72 communicates a signal output from each of the AWGs 200 to the ONU 60. For example, the first non-edge 埠 220c output from the AWG 200 has a wavelength λ ₁ The first signal is separated by a power splitter 72 and will then have a wavelength λ ₁ The first signal is transmitted to and transmitted with a wavelength λ ₁ The first signal separator 72 is optically coupled to the ONU 60. In this case, the first ONU 60a, which uses one of the G-PON MACs ONU 60a, receives the wavelength λ transmitted from the first OLT 50aa. ₁ The output signal. The second ONU 60k may use one of the G-PON MACs ONU 60k (as shown in FIG. 5A) or a 10G-PON ONU 60a (as shown in FIG. 5B) and receive/transmit from/to the second OLT 50ab. Wavelength λ ₂ One of the signals, the second OLT 50ab is one of the G-PON MACs (as shown in Figure 5A) or a 10G-PON OLT (as shown in Figure 5B). Each ONU 60a, 60k includes a bandpass filter 64 that filters the wavelengths that the ONU 60 can receive (Figs. 5C and 5D). Referring to FIG. 6A and FIG. 6B, in order to upgrade or increase the capacity of the upgraded TWDM-PON architecture 100, the band multiplexer 310 including four ports 312a, 312b, 312c, 312d and using the first port 312a and the second port 312b is extended. The use of the third 312c and the fourth 312d. Wavelength λ _n,m Indicates the nth wavelength of the FSR m of the AWG 埠220. For example, wavelength λ _1,1 Indicates the first wavelength λ of the first FSR B1 for upstream transmission (or the third FSR B3 for downstream transmission) ₁ . Wavelength λ _2,1 Indicates the second wavelength λ of the first FSR B1 for upstream transmission (or the third FSR B3 for downstream transmission) ₂ . 6A shows a TWDM network 100 similar to FIG. 5A with two OLTs 50aa, 50ab using a G-PON MAC; and FIG. 6B shows a TWDM network 100 similar to FIG. 5B with G-PON One of the MAC OLT 50aa and one 10G-PON OLT 50ab. Referring to Figure 7, for upgrading/expanding the upgraded TWDM-PON 100, the ISP will first stack the newly upgraded or extended OLT 50, 50ba to 50bn first on the extended FSR B2, B4. The end user 30 can then exchange its legacy ONU 60 with the upgraded ONU 60 configured to receive the updated signals from the extended FSRs B2, B4. After all the old ONUs 60 have been swapped out with the newly upgraded ONU 60, the old OLT 50, 50aa to 50an can be discarded, so that the FSR (for example, FSR B1 and FSR B2) that was originally occupied can be used to upgrade to even more New service. As shown, legacy systems use FSR B1 and B3 and use FSR B2 and B4 in an extended or upgraded system; however, older systems can use FSR B2 and B4 and use FSR B1 and B3 in an extended or upgraded system. The optical system 300 of Figure 7 additionally includes a downstream multiplexer 320c for multiplexing the signals from the OLT 50 (in the L blue band) and for receiving signals from the ONU 60 (in the C blue band) Medium) Demultiplexing one of the multiplexers 320d. Band multiplexer 310 will upstream OLT signal S _UM (in C red band and C blue band) and downstream OLT signal S _DM (in the L red band and the L blue band) multiplexed into one transmission signal S _T signal. The optical system 300 is designed to use a downstream multiplexer 320c to pass downstream signals S from one or more OLTs 50ba to 50bn. _D1 To S _Dn Multiple work into a downstream signal S _DM And using an upstream demultiplexer 320d to pass the multiplex upstream signal S _UM Demultiplexing to one or more upstream signals S to each OLT 50ba to 50bn _U1 To S _Un . In an embodiment, the optical system 300 can include a second signal booster 330b and/or a second signal preamplifier 340b in the downstream and upstream directions, respectively (except for devices similar to those described above) The first signal booster 330a and/or a first signal preamplifier 340a). The use of EDFAs 330b, 340b as part of optical system 300 is optional and depends on the scope and size of the upgraded TWDM-PON 100. In some embodiments, the additional pair of FSRs B2, B4 allows two upgraded services to coexist on the same fiber optic device 20, for example 10G-PON and 100G pt-2pt. As shown, 1G-PON and 10G point-to-point services are supplied through the first FSR B1 and third FSR B3 of the cyclic AWG 200, while the 10G-PON and 100G point-to-point services pass through the second FSR B2 and the fourth FSR B4 of the cyclic AWG 200. Come to supply. With this design, each splitter can be connected to a 1G-PON ONU or 10G-PON ONU, and each point-to-point link can be a 10G link or a 100G link. The ONU 60 uses a tunable laser with a suitable tuning range for upstream transmission and uses a built-in band filter in front of the receiver to select the correct service wavelength. The services received by each user are therefore completely controlled by the ONU hardware. The WDM band multiplex filter 74 is used to separate point-to-point services that are stacked on the same AWG output port. Referring to Figures 8A and 8B, in certain embodiments, the upgraded TWDM-PON 100 uses C and L bands for upstream and downstream transmission, respectively. Each of the C band and the L band is further isolated into two FSRs B1 to B4, blue (short wavelength) and red (long wavelength). The number of wavelengths in each FSR depends on the channel spacing. For 100 GHz spaced wavelengths, each FSR can support approximately 20 wavelengths. In some instances, the old OLTs 50aa through 50an using FSR B1 and B3 use short wavelengths (i.e., blue) for each of the C and L bands (Fig. 8A). However, in other examples and as shown in Figure 8B, the legacy OLT 50aa uses long wavelengths (i.e., red) and the extended or updated system uses short wavelengths (i.e., blue). The C-band and L-band wavelengths for WDM-PON and TWDM-PON provide the lowest loss of glass fiber, thus providing longer transmission distances and lower power transmission. In addition, the C-band and the L-band are EDFAs that are easily amplified, which is the most mature fiber technology. This allows for the implementation of longer transmission distances and very large COs. In addition, since the DWDM economic system already exists in the C band and the L band, it is easy to obtain WDM and tunable laser in the C band and the L band. Referring to Figures 9A and 9B, which show a current TDM architecture compared to one of the upgraded TWDM architectures 100, the system of Figure 9A shows a branch of a fiber optic cable in a typical fiber optic equipment. The size of the bundle becomes smaller as the fiber gets closer to the end user ONU 60. This figure shows a larger sized pipe for a thicker cable that is closer to the CO 40. In contrast, small-sized pipes are used for the upgraded TWDM-PON 100. In fact, a standard single-size pipe can be used for all configurations, simplifying the upgraded TWDM-PON 100 design. The upgraded TWDM-PON 100 design allows for the use of less CO 40, as each CO 40 can be servoed to more ONUs. Thus, the centralization of the CO 40 simplifies operation of the upgraded TWDM-PON 100 and saves on ongoing operating costs due to the need for less CO and therefore fewer staff to manage and operate the network. From the CO to the end user 30, the fiber optic cables 20, 22 pass through several branches to servo in different regions. As illustrated in Figure 9A, a typical network begins with a very wide backbone and branches 22 become thinner and smaller, which also reduces the required pipe size. Larger pipes are slower and more expensive to construct than thinner pipes. In fact, the reduction in the size of the feeder fibers 20, 22 is sufficiently significant that a single size pipe can be used from the CO 40 to the end user 30 through the upgraded TWDM-PON 100. This not only reduces the cost and time of fiber optic equipment 20, 22 construction, but also simplifies the upgraded TWDM-PON 100 design (so that only route design is required and there is no need to worry about pipe size). It also improves the speed of the network design and the licensing process. Referring to Figure 10, a method 1000 for upgrading/expanding an upgraded TWDM network 100 (as illustrated in Figures 4-8 and 9B) is included at block 1002 at a first multiplexer (MUX) 320a. Receiving the following signals and performing multiplex/demultiplex between the following signals: a first multiplexed signal S _DM And a first optical line terminal signal S having a first multiplex group (TDM-PON) _D1 And a second optical line terminal signal S having a second multiplex group (point to point) _Dn . At block 1004, method 1000 includes receiving the following signals at a second multiplexer 320b and performing multiplexing/demultiplexing between the following signals: a second multiplexed signal S _UM And a third optical line terminal signal S having the first multiplex group (TDM-PON) _U1 And having the fourth optical line terminal signal S of the second multiplex group (point to point) _Un . At block 1006, method 1000 includes receiving, at a third multiplexer 310 (eg, a BAND MUX) optically coupled to first multiplexer 320a and second multiplexer 320b, between the following signals Perform multiplex/demultiplex: a feeder optical signal S _Ta ; with the first multiplex signal S _DM And the second multiplex signal S _UM . First optical line terminal signal S _D1 (TDM-PON, λ ₁ And the second optical line terminal signal S _Dn (point-to-point) each containing one of the wavelengths in the old downstream free spectral range FSR B3 or FSR B4, and the third optical line termination signal S _U1 And fourth optical line terminal signal S _Un Each contains one of the wavelengths in the old free spectral range FSR B1 or FSR B2. The method 1000 can further include amplifying the first multiplexed signal S at one of the first amplifiers 330a optically coupled to the first multiplexer 320a and the third multiplexer 310 (BAND MUX). _DM Or amplifying the second multiplexed signal S at a second amplifier 340b optically coupled to the second multiplexer 320b and the third multiplexer 310 (BAND MUX) _UM . In some examples, the first multiplex group includes a TDM-PON protocol and the second multiplex group (peer-to-peer) includes a WDM-PON protocol. First optical line terminal signal S _D1 And the third optical line terminal signal S _U1 Can each have a first agreement (TDM-PON, λ ₁ , for example, 1G-PON), and the second optical line terminal signal S _Dn And fourth optical line terminal signal S _Un Each may have a second agreement (10G point-to-point) different from one of the first agreements. In certain embodiments, the method 1000 further includes receiving the following signals at the first multiplexer 320a (MUX) and performing multiplex/demultiplexing between the following signals: the first multiplexed signal S _DM ; with a fifth optical line terminal signal S _D2 (TDM-PON, λ _2,1 ), the first optical line terminal signal S _D1 (TDM-PON, λ _1,1 And the second optical line terminal signal S _Dn (peer to peer). First optical line terminal signal S _D1 Has a first agreement (TDM-PON, λ _1,1 , for example, 1G-PON), and the fifth optical line terminal signal S _D2 (TDM-PON ₁ ) has a first multiplex group (TDM-PON) and is different from the first protocol (TDM-PON, λ) _1,1 , for example, 1G-PON), a second agreement (TDM-PON λ _2,1 For example, 10G-PON). The method 1000 also includes receiving the following signals at the second multiplexer 320b and performing multiplexing/demultiplexing between the following signals: a second multiplexed signal S _UM ; with the second optical line terminal signal S _DN Fourth optical line terminal signal S _U2 (point-to-point) and a sixth optical line terminal signal S _U2 (TDM-PON). Sixth optical line terminal signal S _U2 Has a first multiplex group (TDM-PON) and a second protocol (TDM-PON λ _2,1 ), as shown in Figure 6B. The method 1000 can also include transmitting the feeder optical signal S by one of the feeder fibers 20 optically coupled to the third multiplexer 310 (BAND MUX). _Ta . The method 1000 also includes receiving the following signals at one of the AWGs 200 optically coupled to the feeder fiber 20, and multiplexing/demultiplexing between the following signals: the feeder optical signal S _Ta And optical network unit signal 50 ₁ To 50 _n . Each optical network unit signal 50 ₁ To 50 _n The upstream wavelength of one of the old-type upstream free-spectrum range FSR 1 or FSR 2 and one of the old-type downstream free-spectrum range FSR 3 or FSR 4 are included. With additional reference to FIG. 7, in some embodiments, method 1000 includes receiving the following signals at one of fourth multiplexers 320c (MUX) optically coupled to third multiplexer 310, and multiplexing between the following signals / Solution multiplex: a third multiplex signal S _Dm+ And a fifth optical line terminal signal S having one of the first multiplexed groups (TDM-PON) _D1 And a sixth optical line terminal signal S having a second multiplex group (point to point) _Dn . The method 1000 also includes receiving the following signal at one of the fifth multiplexers 320d optically coupled to the third multiplexer 310, and performing multiplexing/demultiplexing between the following signals: a fourth multiplexed signal S _UM+ And a seventh optical line terminal signal S having one of the first multiplexed groups (TDM-PON) _U1 And an eighth optical line terminal signal S having a second multiplex group (point to point) _Un . Fifth optical line terminal signal S _D2 And the sixth optical line terminal signal S _Dn Each has a wavelength in an upgraded upstream free spectral range FSR 1 or FSR 2, and a seventh (TDM-PON) optical line termination signal S _U1 And the eighth optical line terminal signal S _Un (Point-to-point) each has a wavelength in an upgraded downstream free spectral range FSR 3 or FSR 4. The method 1000 can further include transmitting the feeder optical signal S by one of the feeder fibers 20 optically coupled to the third multiplexer 310 (BAND MUX) _Ta . The method 1000 also includes receiving the following signals at one of the AWGs 200 optically coupled to the feeder fiber 20, and multiplexing/demultiplexing between the following signals: the feeder optical signal S _Ta And optical network unit signal 50 ₁ To 50 _n . Each optical network unit signal 50 ₁ To 50 _n One of the old upstream wavelengths included in the old upstream free spectral range FSR 1 or FSR 2, one of the old downstream free spectral range FSR 3 or FSR 4, the old downstream wavelength, and one of the upgraded upstream free spectral ranges Upgrade the upstream wavelength and upgrade the second downstream wavelength in one of the upgraded downstream free spectral ranges. Several embodiments have been described. It will be understood, however, that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are also within the scope of the following claims. For example, the actions recited in the scope of the claims can be performed in a different order and still achieve a desired result.

10‧‧‧ Passive optical network

20‧‧‧Feeder Fiber/Trunk Fiber/Fiber/Fiber Device/Fiber Bundle/Feeder Fiber Stranded Wire/Rough Fiber Cable/Coarse Fiber/Feeder Cable

22‧‧‧Optical/Specific Path/Fiber Optic Equipment/Fiber Bundle/Feeder Fiber/Feeder Fiber Stranded Wire

30‧‧‧End User/User/User

40‧‧‧ Central Bureau

42‧‧‧Video media distribution

44‧‧‧Internet data

46‧‧‧Voice data

50‧‧‧Transceiver/Optical Transceiver/Optical Line Terminal/Optical Line Terminal Transceiver

50a‧‧‧Optical line terminal/optical line terminal transceiver

50aa‧‧‧optical line terminal/old optical line terminal/first optical line terminal

50ab‧‧‧second optical line terminal/third optical line terminal

50an‧‧‧Study line terminal/old optical line terminal/second optical line terminal

50b‧‧‧Optical Line Terminal/Optical Line Terminal Transceiver

50ba‧‧‧Optical line terminal

50bb‧‧‧First optical line terminal

50bn‧‧‧optical line terminal / second optical line terminal

50n‧‧‧Optical line terminal/optical line terminal transceiver

52‧‧‧Optical wavelength duplexer/duplexer

60‧‧‧Optical Network Unit/Transceiver

60a‧‧‧Optical Network Unit / First Optical Network Unit

60k‧‧‧Optical Network Unit / Second Optical Network Unit

60n‧‧‧Optical Network Unit

62‧‧‧ Wavelength Specific Transmitter/Duplexer

64‧‧‧Bandpass filter

65‧‧‧Tuneable transmitter

66‧‧‧Receiver/tunable receiver

70‧‧‧Remote node/passive remote node

72‧‧‧Power splitter/optical power splitter/separator/optical splitter

74‧‧‧Wavelength division multiplexed-band multiplex filter

100‧‧‧Updated wavelength division multiplexed optical passive network architecture / upgraded time wavelength division multiplexed optical passive network architecture / time wavelength division multiplex optical passive network architecture / network / upgraded time wavelength division Work optical passive network / optical network / system / time wavelength division multiplexing network / upgraded time wavelength division multiplexing architecture

200‧‧‧wavelength multiplexer/wavelength demultiplexer/field array waveguide grating router/array waveguide grating router/circular array waveguide grating router/multi-cycle array waveguide grating router/array waveguide grating

200a‧‧‧wavelength multiplexer

200b‧‧‧wavelength demultiplexer

210‧‧‧Entry埠/Input

210a‧‧‧First Input/Input

220‧‧‧Export 埠/output/埠/array waveguide grating output

220a‧‧‧埠/output/output埠/first output/edge input埠

220b‧‧‧埠/output/output埠/second output

220c‧‧‧埠/output/output埠/third output

220d‧‧‧埠/output/output埠/fourth output

220m‧‧‧埠/output/output埠

220n‧‧‧埠/output/output埠

300‧‧‧Optical system

310‧‧‧Multiplexer/band multiplexer/third multiplexer

312a‧‧‧埠/埠

312b‧‧‧埠/第二埠

312c‧‧‧埠/third

312d‧‧‧埠/四埠

320‧‧‧Multiplexer

320a‧‧‧Downstream multiplexer/first multiplexer

320b‧‧‧Solution multiplexer/upstream solution multiplexer/second multiplexer

320c‧‧‧Downstream multiplexer/fourth multiplexer

320d‧‧‧Solution multiplexer/upstream solution multiplexer/fifth multiplexer

330‧‧‧First Amplifier/Budded Fiber Amplifier

330a‧‧‧First Signal Amplifier/First Amplifier

330b‧‧‧Second Signal Amplifier/Doped Fiber Amplifier

340‧‧‧Signal Preamplifier/Signal Amplifier/Budded Fiber Amplifier/Budded Fiber Amplifier Signal Amplifier/Secondary Amplifier

340a‧‧‧First Signal Preamplifier / Second Amplifier

340b‧‧‧second signal preamplifier/secondary amplifier/doped fiber amplifier

B1‧‧‧Free Spectrum Range/Cycle/First Free Spectrum Range/Upstream Free Spectrum Range/Short Wavelength Band

B2‧‧‧Free Spectrum Range/Cycle/Second Free Spectrum Range/Upstream Free Spectrum Range/Short Wavelength Band

B3‧‧‧Free spectrum range/cycle/third free spectrum range/downstream free spectrum range/longer wavelength band

B4‧‧‧Free spectrum range/cycle/fourth free spectrum range/downstream free spectrum range/longer wavelength band

P1‧‧‧ first

P2‧‧‧Second

P3‧‧‧third

Rx‧‧‧ Receiver

S _D1 ‧‧‧downstream signal/signal/first optical line termination signal/fifth optical line termination signal

S _D2 ‧‧‧Downstream signal/signal/fifth optical line termination signal

S _DM ‧‧‧ downstream signal / multiplex downstream signal / first multiplex signal / downstream optical line terminal signal

S _DM+ ‧‧‧ third multiplex signal

S _Dn ‧‧‧downstream signal/signal/second optical line termination signal/sixth optical line termination signal

S _Ta ‧‧‧ feeder optical signal

S _U1 ‧‧‧Upstream signal/signal

S _U2 ‧‧‧Upstream signal/signal

S _UM ‧‧‧Upstream signal / multiplexed upstream signal / second multiplexed signal / upstream optical line termination signal

S _UM+ ‧‧‧ fourth multiplex signal

S _Un ‧‧‧Upstream signal/signal/third optical line termination signal/seventh optical line termination signal

λ ₁ ‧‧‧wavelength / first wavelength

λ ₂ ‧‧‧wavelength/second wavelength

λ ₃ ‧‧‧wavelength/third wavelength

λ ₄ ‧‧‧wavelength/fourth wavelength

λ ₅ ‧‧‧wavelength / first wavelength

λ ₆ ‧‧‧wavelength/second wavelength

λ ₇ ‧‧‧wavelength/third wavelength

λ ₈ ‧‧‧wavelength/fourth wavelength

λ ₉ ‧‧‧wavelength / first wavelength

λ ₁₀ ‧‧‧wavelength/second wavelength

λ ₁₁ ‧‧‧wavelength/third wavelength

λ ₁₂ ‧‧‧wavelength/fourth wavelength

λ ₁₃ ‧‧‧wavelength / first wavelength

λ ₁₄ ‧‧‧wavelength/second wavelength

λ ₁₅ ‧‧‧wavelength/third wavelength

λ ₁₆ ‧‧‧wavelength/fourth wavelength

1 is a schematic diagram of a prior art PON architecture. 2A is a schematic diagram of a prior art TDM-PON architecture. 2B is a schematic diagram of a prior art WDM-PON architecture. 2C is a schematic diagram of a prior art NG-PON2 architecture. 3A is a schematic diagram of an exemplary TWDM-PON architecture. 3B and 3C are schematic views of an exemplary arrayed waveguide grating (AWG). Figure 3D is a schematic illustration of the cyclic behavior of the exemplary AWG of Figures 2A and 2B. 3E is a schematic diagram of one of the cyclic behaviors of the exemplary AWG of FIGS. 2A and 2B in which the same wavelength is used for the uplink and downlink. Figure 4 is a schematic diagram of one of the exemplary TWDM-PON architectures with one Layer 2 service. 5A and 5B are schematic diagrams of an exemplary TWDM-PON architecture. 5C and 5D are schematic diagrams of an exemplary ONU used in the TWDM-PON architecture of FIGS. 5A and 5B. 6A and 6B are schematic diagrams of an exemplary TWDM-PON architecture configured to be upgraded/expanded. 7 is a schematic diagram of an exemplary extended/upgraded TWDM-PON architecture. 8A and 8B are schematic diagrams of exemplary spectrum allocations of an extended/upgraded TWDM-PON architecture. 9A is an exemplary schematic diagram of one prior art TDM-PON network. 9B is an exemplary schematic diagram of an exemplary TWDM-PON network. Figure 10 is an exemplary configuration of one of the operations of upgrading/expanding an old network. Like reference symbols indicate like elements in the various figures.

Claims (12)

A communication system comprising: a central office; a first multiplexer configured to have a time-division-multiplexing passive optical network protocol (time-division-multiplexing passive optical network protocol) One of the first optical line termination signals and one of the second optical line termination signals having a wavelength-division-multiplexing passive optical network protocol is multiplexed into a first multiplexed signal; a second multiplexer configured to demultiplex a second multiplexed signal into a third optical line termination signal having the time division multiplexed passive optical network protocol and having the wavelength division multiplex passive a fourth optical line termination signal of the optical network protocol; a third multiplexer optically coupled to the first multiplexer and the second multiplexer, the third multiplexer configured to a multiplexer/demultiplexing between the feeder optical signal and the first multiplexed signal and the second multiplexed signal; a fourth multiplexer optically coupled to the third multiplexer and grouped State a fifth optical line termination signal having one of the time division multiplexed passive optical network protocols and a sixth optical line termination signal having one of the wavelength division multiplexed passive optical network protocols multiplexed into a third multiplex signal; a fifth multiplexer optically coupled to the third multiplexer and configured to demultiplex a fourth multiplexed signal to have the time division multiplexed passive optical network protocol a seventh optical line termination signal and an eighth optical line termination signal having the wavelength division multiplexed passive optical network protocol, a feeder fiber optically coupled to the third multiplexer and configured to communicate the feed Optical signal; and an array of waveguide gratings optically coupled to the feeder fiber and configured to perform multiplexing/demultiplexing between the feeder optical signal and the plurality of optical network unit signals, each optical network The path unit signal includes one of the legacy upstream free spectral range, one of the old upstream wavelengths, one of the old downstream free spectral ranges, the old downstream wavelength, and an upgraded upstream free spectral range ( One of the upgrade upstream free spectral range) upgrades the upstream wavelength and one of the upgraded downstream free spectral ranges to upgrade the downstream wavelength, wherein each of the first optical line termination signal and the second optical line termination signal is included The old downstream wavelength in the old downstream free spectral range, the third optical line termination signal and the fourth optical line termination signal Each of the old optical upstream wavelengths in the old upstream free spectral range, the fifth optical line termination signal and the sixth optical line termination signal being included in the upgraded downstream free spectral range The upstream wavelength is upgraded, and each of the seventh optical line termination signal and the eighth optical line termination signal includes the upgraded upstream wavelength in the upgraded upstream free spectral range. The system of claim 1, further comprising at least one of: a first amplifier optically coupled to the first multiplexer and the third multiplexer and configured to optically amplify the first Once a multiplex signal; or A second amplifier optically coupled to the second multiplexer and the third multiplexer and configured to optically amplify the second multiplexed signal. The system of claim 1, wherein the first optical line termination signal and the third optical line termination signal each have a first agreement, and the second optical line termination signal and the fourth optical line termination signal each have a different The second agreement of one of the first agreements. The system of claim 1, further comprising: a first optical line termination having an optical connection with the first multiplexer and an optical connection with the second multiplexer, the first optical a line terminal transmitting the first optical line termination signal and receiving the third optical line termination signal; and a second optical line termination having an optical connection with the first multiplexer and outputting the second multiplexer One of the optical connections is input, the second optical line terminal transmits the second optical line termination signal (S _Dn ) and receives the fourth optical line termination signal. The system of claim 1, wherein: the first multiplexer is further configured to multiplex a ninth optical line termination signal with the first optical line termination signal and the second optical line termination signal into the first After the multiplex signal, the first optical line termination signal has a first agreement, the ninth optical line termination signal having the time division multiplexed passive optical network protocol and a second agreement different from the first agreement; And the second multiplexer is further configured to demultiplex the second multiplexed signal into the second optical line termination signal, the fourth optical line termination signal, and a tenth optical line termination signal, the The ten optical line termination signal (S _U2 ) has the time division multiplexed passive optical network protocol and the second protocol. The system of claim 5, further comprising a third optical line termination having an optical connection with the first multiplexer and an optical connection with the second multiplexer, the third optical line termination The ninth optical line termination signal is transmitted and the tenth optical line termination signal is received. The system of claim 1, further comprising at least one of: a third amplifier optically coupled to the fourth multiplexer and the third multiplexer and configured to optically amplify the first A three-pass multiplex signal; or a fourth amplifier optically coupled to the fifth multiplexer and the third multiplexer and configured to optically amplify the fourth multiplexed signal. The system of claim 7, further comprising: a third optical line terminal having one of an output in communication with the fourth multiplexer and an input in communication with the fifth multiplexer, the third optical line terminal Transmitting the fifth optical line termination signal and receiving the seventh optical line termination signal; and a fourth optical line termination having one of communicating with the fourth multiplexer and communicating with the fifth multiplexer Input, the fourth optical line terminal transmits the sixth optical line termination signal and receives the eighth optical line termination signal. A communication method comprising: Receiving the following signals at one of the first multiplexers of a central office, and performing multiplex/demultiplexing between the following signals: a first multiplexed signal; and having a time division multiplexed passive optical network protocol a first optical line termination signal and a second optical line termination signal having a wavelength division multiplexed passive optical network protocol; receiving the following signals at one of the second multiplexers of the central office, and in the following signals Multiplex/demultiplexing: a second multiplexed signal; and a third optical line termination signal having the time division multiplexed passive optical network protocol and having the wavelength division multiplexed passive optical network agreement a fourth optical line termination signal; receiving the following signal at a third multiplexer optically coupled to the first multiplexer and the second multiplexer, and performing multiplex/demultiplexing between the following signals : a feeder optical signal; and the first multiplexed signal and the second multiplexed signal; receiving the following signal at a fourth multiplexer of the central office optically coupled to the third multiplexer, And between the following signals Work/demultiplexing: a third multiplexed signal; a fifth optical line termination signal having one of the time division multiplexed passive optical network protocols and a sixth of the wavelength division multiplexed passive optical network protocol An optical line termination signal; and received at a fifth multiplexer of the central office optically coupled to the third multiplexer Down signal, and multiplexing/demultiplexing between: a fourth multiplexed signal; and a seventh optical line termination signal having the time division multiplexed passive optical network protocol and having the wavelength division An eighth optical line termination signal of a multiplexed passive optical network protocol; transmitting the optical signal of the feeder by one of the optical fibers optically coupled to the third multiplexer; and optically connecting to the optical fiber of the feeder Receiving the feeder optical signal and the plurality of optical network unit signals at the arrayed waveguide grating and performing multiplexing/demultiplexing between the feeder optical signal and the optical network unit signals, each optical network unit signal including Upgrading the upstream wavelength and upgrading the downstream free spectrum in one of the old upstream free spectral range, one of the old downstream downstream free spectral range, one of the old upstream downstream wavelengths, and one of the upgraded upstream free spectral ranges One of the ranges upgrades the downstream wavelength, wherein each of the first optical line termination signal and the second optical line termination signal is included downstream of the old type Depending on the old downstream wavelength in the spectrum range, each of the third optical line termination signal and the fourth optical line termination signal includes the old upstream wavelength in the old upstream free spectral range, the first Each of the fifth optical line termination signal and the sixth optical line termination signal includes the upgraded downstream wavelength in the upgraded downstream free spectral range, and the seventh optical line termination signal and the eighth optical line termination signal Each of these includes the upgraded upstream wavelength in the upstream free spectral range of the upgrade. The method of claim 9, further comprising: Amplifying the first multiplexed signal at a first amplifier optically coupled to the first multiplexer and the third multiplexer; or optically connecting to the second multiplexer and the third multiplexer One of the second amplifiers amplifies the second multiplexed signal. The method of claim 9, wherein the first optical line termination signal and the third optical line termination signal each have a first agreement, and the second optical line termination signal and the fourth optical line termination signal each have a different The second agreement of one of the first agreements. The method of claim 9, further comprising: receiving the following signal at the first multiplexer, and performing multiplex/demultiplexing between: the first multiplexed signal; and a ninth optical a line termination signal (S _D2 ), the first optical line termination signal, and the second optical line termination signal, wherein the first optical line termination signal has a first agreement, and the ninth optical line termination signal has the time division a multiplexed passive optical network protocol and a second protocol different from the first protocol; and receiving the following signals at the second multiplexer and performing multiplex/demultiplexing between the following signals: the second a multiplexed signal; the second optical line termination signal, the fourth optical line termination signal, and a tenth optical line termination signal, wherein the tenth optical line termination signal has the time division multiplexed passive optical network protocol The second agreement.